My short springs were designed to minimize the problem caused by the poorly designed stock steering stem. They will do that when used with a stock steering stem.
The red springs, which were 75 lbs/in., worked on my racer very well and are still in use with the present owner. On all my springs I used the original stock figures for bottoming out in an effort to prevent it from happening. To get to that rather stiff figure to prevent bottoming out, the spring had to be reasonably stiff. But, because the spring could start at 0 lbs/in. it mitigated the stiffness quite a bit. It goes up quite fast to prevent the bottoming out problem. Finally, it made some sense to have a "softer" spring to use with other heavier springs to cover all the weight variations.
Once the stem is changed, you should not need to worry about the geometry problem. You can pull the brake lever and the fork will still be able to go up and down. If you have a new stem you can use any combination of springs you wish. The limitations are comfort and performance and should not involve the safety issues that have caused issues in the past.
The DD stem is not quite the same as the JE stem. They both solve the geometry problem, but the JE stem has a good amount of telescopic motion, which is welcomed by most modern riders. The DD stem does not have telescopic motion, it is more like a girder fork where the wheelbase changes little. The design differences exist because I did not know John Emanuel and he did not know me. We both chose slightly different designs and we both worked alone, at least I did and I suspect John did, also.
I suspect that the differences in spring and damper choice is due to the need to counteract the attitude changes that come with the JE design. Some have chosen stiffer springs and some have chosen stiffer dampers. I would tend to choose soft damping with stiffer springing, but this is normally something the manufacturer works out preprodution. Unfortunately, the messy work of testing is being conducted by all of the participants. The good news is that the quest is now for comfort and no longer involves safety.
David